Authorities said Santiago, a former Army National Guard soldier and an Iraq war veteran, fired several shots from three magazines before running out of ammunition. Santiago then sprawled on the ground and laid spread eagle, waiting for police to arrive. Santiago opened fire with a Walther 9mm semi-automatic handgun that he legally checked on a flight from Alaska.

As authorities continue to gather information on the man, chilling tidbits about his actions prior to the massacre have been revealed.